Filtering apparatus



Sepe. 2s, 1937. l CARHGNY 2,094,350A

' FILTERING APPARATUS Filed June'25, 1936 Jin/ef? for: 1*

Patented sept. v2s, 1937 y 2,094,350

N i UNITED sTATEs PATENT oI-Flcs` FIL'rEmNG Arramvrns` Georges Louis Desire Cartigny, Rieme-Gent, Belgium, assignor to Aktebolaget Kemiska Patenter, Landskrona, Sweden, a Swedish company y v Application June 23, 1936, Serial No. 86,759

In France June` 26, 1935 5 Claims. (Cl. 210-197) This invention relates to apparatus for filtering the various washing periods can be regulated as mixtures of solid and liquid substances. desired. Further,v there may be arranged above For filtering mixtures of solid and liquid subthe bandwhich' runs over the suction box and on stances and for washing the filter cake it is known the surface of the lter cake which is formed, to employ apparatus in which an endless elastic sliding or rolling members, for example separating carrier band is carried by means of guide rollers walls, rollers or the like, which separate the vvariover one or more suction boxes which are narous washing liquors one from another. rower than the band, and the actual filtering me- I have found in practical operation that even dium, for example filter cloth, is arranged on .the with the use of conveyor bands having upstandcarrier band. l i ing reinforcing edges, it is frequently difllcult to l0 In a known apparatus of this kind (see for exprevent part of the filter cake from escaping into ample the French Specification No. 760,349) the the suction box at the places where the edges endless carrier band of elastic material, for exof the filter medium or intermediate belt bears ample rubber, moves in a horizontal plane and is against the reinforcing edge, and thus adversely o provided with openings, and is covered with a affecting the filtering and washing action. l5 suitable filtering medium, for example'fllter cloth, The object of the present invention is' greatly The carrier band is guided in such a way that its to improve this type of apparatus for filtering lower surface passes over and automatically mixtures of solids and fluids andffor washing the makes tight contact with theA smooth and even lter cake, and to obviate the aforesaid difficulties edges of one or more suction boxes, which are arwhich are encountered in` the operation of such 20 ranged below and are open to the band, in which apparatus. In accordance with my invention, I a vacuum is maintained. The filtrates are drawn accomplish this object by making the upstanding off separately or in common into the suction boxes, reinforcing edges of the eonveyer bend of a while the filter cake which is formed on the fllterheight Such that they project freely from the ing medium is removed on the return movement outer surface of the band on which the interme- 25 of the endless band, being preferably thrown on diate band rests to a distance at least substanautomatically. In one particular form of such tielly equal to the thickness Of the intermediate apparatus, the elastic carrier band is provided band. I also make the filteringmedium wider with upstanding reinforcing edges within which than 'the intermediate bandl and arrange it A`on the filtering medium is disposed and between the common surface formed by the intermediate 30 which there is preferably room for the whole or band and the upper surface of the reinforcing at least a part of the filter cake. f According to a edges Constructed in the manner JuSt deflned. further form of construction there is arranged Furthermore, the lateral parts ofthe conveyor between the'carrier band and the filtering meband projecting beyond the suction box or boxes dium a separate endless band which is also elastic are troughed in CIOSS Section by being upwardly 35 and is porous or perforated or otherwise made curved, at least'during the passage of the con-v permeable in a vertical direction. This intermeveyer band over the suction box or boxes. diate band may be provided on its inner surface The construction just described provides an abalso with ribs, bars or knobs or other projections solutely reliable and simple arrangement by which 40 in orderto form cells or cavities between the the filter medium encloses the filter cake laterally 40 carrier band and intermediate band and thereby and prevents any possibility of itsescape to the uniformly to distribute the vacuum over the suction boxes between the lter medium and the vunder surface of the filtering medium. When intermediate or conveyor band, more particularly elastic'carrier bands with upstanding reinforcing aS the ,tenSlOh Caused by formation of the edges are employed, the intermediate band and,y troughed cross section presses the several belts 45 the filtering medium which rests on it lie between tightly against one another and thus produces a these upstanding edges between which also the particularlyeifective packing. n filter cake is then formed. The troughing eiectreferred to above, which According to further forms of construction, the takes place at least for the distance of travel suction boxes are arranged so as to be movable or over the suction boxes, may be most simply 50 adjustable in the vertical and/or in the horizontal achieved by the provisionof suitable guide means, plane. Also, in addition to or instead `of this which may comprise rollers,guide 'bars or the adjustment, transverse partitions may be arl like, and preferably by being suitably graduated ranged inside the suction box, these partitions or stepped are arranged to present a smooth tranbeing adjustable or hinged so that the length of sition from the troughed cross section to the nat 55 cross section which is requisite for the guide drums.

A particularly suitable arrangement according to the invention is one in which the upstanding reinforcing edges of the conveyor belt are each provided with one or more grooves which preferably extend the entire length of the edge and also preferably increase in cross section inwardly. The marginal portions of the filter medium, for example the filter cloth, may be secured in these grooves, and to ensure the cloth being held in proper position I may provide clamping means such as rubber wedges, wooden plugs or the like which are wedged at intervals in the grooves after the marginal portion of the cloth has been inserted therein. This additional precaution is particularly advantageous for preventing loosening of the filter medium from the intermediate or conveyor band at that part of the apparatus in which the conveyor band is above the filter medium.

To further increase the tensioning and packing effect resulting from the troughed cross section of the conveyor band, it is desirable to provide the inside of the permeable intermediate belt, which may for example consist of a perforated rubber web, with solid marginal flanges which, at least during the troughing of the conveyor belt, closely engage the lateral inner surfaces of the upstanding reinforcing edges of this band.

The invention illustratively exemplified in the accompanying drawing, in which Figure l is a side elevation of one form of the apparatus;

Figure 2 is a cross section thereof on a larger scale, and

Figures 3 and 4 are fragmentary sectional views of modifications.

Referring to the drawing, a is a perforated, endless elastic conveyor band having upstanding edges of the same material, for example rubber,

` as the band itself. The band travels in a horizontal plane over drums b and c, one at least of which is driven. d denotes the suction box, which may be adjustable if desired and has wide supporting ledges over which the belt a glides, so

' that the band automatically makes a tight contact.

superimposed on the belt a is a perforated, endless intermediate band e. Superimposed on the intermediate band e is a filter cloth j in the form of an endless band. On the surface which faces the conveyor band a the intermediate band e isprovided with projections in the form of ribs, bars, buttons or the like, so that between the two bands interstices or chambers are produced which facilitate uniform distribution of the reduced pressure under the lter cloth.

As shown more particularly in Figure 2, the reinforcing edges g of the conveyor belt a are so formed that they extend on the inside to a height which is substantially equal to the thickness of the intermediate belt e. Upon the common surface, thus formed, I place the filter cloth f which extends to the outer line of the reinforcing edges g.

In the form illustrated, the troughed cross section for the distance of travel over the suction box is effected by guide and are so arranged that before and after passing the suction box they permit the transition of the upwardly bent edges into the horizontal position, whereupon the whole surface of the belts passes over the drums b and c.

Figure 2 further shows that the resulting filter cake i is also enclosed laterally by the filter cloth on the stretch of the band above the suction box so that all possibility of escape of the cake to the suction box is prevented. In the transition to the fiat or untroughed cross section the filter cloth separates laterally from the filter cake and thus facilitates discharge of the cake at the appropriate drum.

Figure 3 illustrates a particularly suitable construction of the reinforcing edge g and fastening of the filter cloth thereto. In this form of the apparatus the reinforcing edge g is provided with a groove k in which the marginal portion of the lter cloth f of appropriate width, is clamped. Additional security is obtained by insertion of the plug l, which may be of rubber or wood, and ensures that the filter cloth is held in its proper position even on the under side of the apparatus.

Figure 4 illustrates a particularly suitable construction of the intermediate band e, in that the band is provided at each side with a solid inwardly extending rim m which closely engages the inner surface of the reinforcing edge y, Darticularly during the troughing of the conveyor belt, and thus contributes to the desired packing effect, i. e. to making a tight joint between the two bands.

I claim:

1. A filter apparatus for the purpose specified, comprising a suction box, a perforated conveyor band adapted to travel over said suction box,

an intermediate perforated band superimposed on said conveyor band, vacuum distributing chambers between said bands, said conveyor band having upstanding lateral reinforcing edges of a height at least substantially equal to the thickness of said intermediate band whereby the upper surface of said intermediate band and the upper surfaces of said edges lie in a common plane and a filter medium super-imposed on said plane and extending from side to side of said edges.

2. A filter apparatus for the purpose specified. comprising a suction box, a perforated conveyor band adapted to travel over said suction box and having upstanding lateral reinforcing edges provided with grooves therein, an intermediate perforated band superimposed on said conveyor band and of a thickness approximately equal to the height of said edges whereby the upper surface of said intermediate band and the upper surfaces of said edges lie in a common plane and a filter medium superimposed on said intermediate band, said filter medium being wider than said conveyor band and having its edges received in said grooves.

3. A filter apparatus for the purpose specified, comprising a suction box, a perforated conveyor band adapted to travel over said' suction box and having upstanding lateral reinforcing edges each provided with a groove throughout its length Widening downwardly in cross section, an intermediate perforated band superimposed on said conveyor band and of a thickness approximately equal to the height of said edges whereby the upper surface of lsaid intermediate band and the upper surfaces of said edges lie in a common plane and a filter cloth of greater width than said conveyor belt superimposed on said intermediate band and having its side edges secured in said grooves.

4. Afllter apparatus for the purpose specified, comprising a suction box, a. porforated conveyor band adapted to travel over said suction box and having upstanding lateral reinforcing edges, an intermediate band superimposed on said conveyor band, said intermediate band having solid lateral marginal portions snugly engaging the inner faces of said reinforcing edges and said intermediate band being of a thickness substantially equal to the height of said reinforcing edges whereby the upper surfaces of said intermediate band and the upper surfaces of said reinforcing edges lie in a common plane, vacuum distributing chambers between said bands, and a lter cloth superimposed on said plane and extending from side to side of said edgesl 5. A lter apparatus for the purpose specied, comprising a suction box, a perforated conveyor band adapted to travel over said suction box and having upstanding lateral reinforcing edges each provided with a groove throughout its length 

